Fc receptor-like molecules.

Division of Developmental and Clinical Immunology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294-3300, USA.
Annual Review of Immunology (Impact Factor: 41.39). 02/2007; 25:525-60. DOI: 10.1146/annurev.immunol.25.022106.141541
Source: PubMed

ABSTRACT Discovery of a large family of Fc receptor-like (FCRL) molecules, homologous to the well-known receptors for the Fc portion of immunoglobulin (FCR), has uncovered an impressive abundance of immunoglobulin superfamily (IgSF) genes in the human 1q21-23 chromosomal region and revealed significant diversity for these genes between humans and mice. The observation that FCRL representatives are members of an ancient multigene family that share a common ancestor with the classical FCR is underscored by their linked genomic locations, gene structure, shared extracellular domain composition, and utilization of common cytoplasmic tyrosine-based signaling elements. In contrast to the conventional FCR, however, FCRL molecules possess diverse extracellular frameworks, autonomous or dual signaling properties, and preferential B lineage expression. Most importantly, there is no strong evidence thus far to support a role for them as Ig-binding receptors. These characteristics, in addition to their identification in malignancies and autoimmune disorders, predict a fundamental role for these receptors as immunomodulatory agents in normal and subverted B lineage cells.

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    ABSTRACT: Abstract Previous studies have identified several single nucleotide polymorphisms (SNPs) of Fc receptor-like 3 (FCRL3), an excellent susceptibility gene, as predisposing factors for human autoimmune diseases (ADs). However, the results remain inconclusive. To assess the effect of four selected SNPs (rs7528684, rs11264799, rs945635 and rs3761959), we conducted a meta-analysis with 34 case-control studies. Summary odd ratios (ORs) and 95% confidence intervals (95% CIs) for the polymorphisms in FCRL3 and ADs risk were evaluated. Furthermore, this meta-analysis was performed by using allele comparisons, as well as stratified analyses by ethnicity and disease phenotypes under different genetic models. Our data showed that the TC, TT + TC genotypes of rs7528684 contributed to a lower risk of ADs, compared with the CC carriers (OR = 0.91, 95% CI = 0.85-0.97; OR = 0.91, 95% CI = 0.85-0.98). In comparison with rs7528684 TC genotype, the TT + CC carriers were significantly associated with higher ADs risk (OR = 1.03, 95% CI = 1.00-1.07). In terms of stratified analyses by ethnicity and disease phenotypes, there were significant associations of rs7528684 polymorphism both with ADs in Asians and Europeans, and with rheumatoid arthritis, Graves' disease, type-1 diabetes, and other ADs under different genetic models. Moreover, significant associations were also found to be correlated with ADs risk for the SNP rs11264799 in mixed subgroup, for rs945635 in Europeans, North Americans and mixed group, and for rs3761959 in North Americans. These findings indicate that the polymorphisms in FCRL3 may play a role in the pathogenesis of ADs.
    Autoimmunity 10/2013; · 2.75 Impact Factor
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    ABSTRACT: Receptors interacting with the constant domain of immunoglobulins (Igs) have a number of important functions in vertebrates. They facilitate phagocytosis by opsonization, are key components in antibody-dependent cellular cytotoxicity as well as activating cells to release granules. In mammals, four major types of classical Fc receptors (FcRs) for IgG have been identified, one high-affinity receptor for IgE, one for both IgM and IgA, one for IgM and one for IgA. All of these receptors are related in structure and all of them, except the IgA receptor, are found in primates on chromosome 1, indicating that they originate from a common ancestor by successive gene duplications. The number of Ig isotypes has increased gradually during vertebrate evolution and this increase has likely been accompanied by a similar increase in isotype-specific receptors. To test this hypothesis we have performed a detailed bioinformatics analysis of a panel of vertebrate genomes. The first components to appear are the poly-Ig receptors (PIGRs), receptors similar to the classic FcRs in mammals, so called FcRL receptors, and the FcR γ chain. These molecules are not found in cartilagous fish and may first appear within bony fishes, indicating a major step in Fc receptor evolution at the appearance of bony fish. In contrast, the receptor for IgA is only found in placental mammals, indicating a relatively late appearance. The IgM and IgA/M receptors are first observed in the monotremes, exemplified by the platypus, indicating an appearance during early mammalian evolution. Clearly identifiable classical receptors for IgG and IgE are found only in marsupials and placental mammals, but closely related receptors are found in the platypus, indicating a second major step in Fc receptor evolution during early mammalian evolution, involving the appearance of classical IgG and IgE receptors from FcRL molecules and IgM and IgA/M receptors from PIGR.
    PLoS ONE 05/2014; 9(5):e96903. · 3.53 Impact Factor
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    ABSTRACT: Hepatitis C virus (HCV) is associated with B cell lymphoproliferative disorders, including mixed cryoglobulinemia (MC) vasculitis and B cell non-Hodgkin's lymphoma. The expansion of clonal and autoreactive rheumatoid factor-bearing CD21(-/low) marginal zone (MZ) B cells was demonstrated in patients with HCV-associated MC vasculitis. Fc receptor-like (FCRL) proteins comprise a family of immunoregulatory proteins preferentially expressed on B lineage cells. The goal of this study was to investigate the expression of FCRL proteins 1-5 on B cells from patients with HCV-associated MC vasculitis. Expression of FCRL proteins 1-5 was assessed by flow cytometry on B cells from 15 HCV-infected patients with type II MC (7 of whom had B cell non-Hodgkin's lymphoma), 20 HCV-infected patients without MC, and 20 healthy donors. To evaluate FCRL-5 as an immunotherapy target in HCV-associated MC vasculitis, 2 anti-FCRL-5 recombinant immunotoxins were produced using anti-FCRL-5 monoclonal antibodies and Pseudomonas exotoxin. Expression of FCRLs 2, 3, and 5 was markedly increased while expression of FCRL-1 was decreased on clonal CD21(-/low) MZ B cells, as compared with other B cell subsets, from HCV-infected patients and healthy donors. However, there was no difference in the pattern of FCRL expression between HCV-MC patients with lymphoma and those without lymphoma. The anti-FCRL-5 immunotoxins showed specific cytotoxicity against FCRL-5-expressing clonal CD21(-/low) MZ B cells isolated from HCV-infected patients as well as FCRL-5-transfected cell lines. No cytotoxicity against T cells or conventional B cells was observed. These findings suggest that FCRL-5-targeting therapies could be a specific treatment for HCV-associated MC vasculitis and other FCRL-5-positive autoimmune B cell disorders.
    Arthritis & rheumatology (Hoboken, N.J.). 02/2014; 66(2):433-43.


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